Spring balanced support device

ABSTRACT

A spring balanced support device having at least one arm, connected to its surroundings via a movable pivot point, forming an arm mechanism to which a mass may be coupled directly or indirectly at a mass coupling point, balanced by at least one spring, at one end directly or indirectly connected to the arm mechanism at a spring connection point, the other end directly or indirectly connected to the surroundings at a spring base point, wherein the spring base point is located substantially on an axis which extends through the movable pivot point and substantially parallel to a direction of a force exerted on the spring balanced support device at the mass coupling point due to the force of gravity on the mass, or wherein the spring base point is located at a distance from said axis along a line which intersects the axis and which extends substantially parallel to a pivot point axis of the movable pivot point, wherein the movable pivot point is movable along the axis in order to adjust the spring balanced support device.

FIELD OF THE INVENTION

The present invention relates to a spring balanced support device forcounteracting the force of gravity on a mass. The present inventionfurther relates to several methods of engaging the spring balancedsupport device for different applications. Spring balanced supportdevices are known.

DESCRIPTION OF RELATED ART

U.S. Pat. No. 4,387,876 and U.S. Pat. No. 4,883,249 disclose examples ofspring balanced support devices. These spring balanced support devicescomprise an arm mechanism and a spring which counteracts a weight ofmass. The moment about a pivot point generated by the spring equals themoment generated by the weight of its balanced mass. The devices of U.S.Pat. No. 4,387,876 and U.S. Pat. No. 4,883,249 comprise an adjustingmechanism for adjusting the spring in order to balance a differentweight.

THE INVENTION

-   -   It is an object of the invention to provide an improved spring        balanced support device.        To this end, the invention provides a spring balanced support        device comprising at least one arm, connected to its        surroundings via a movable pivot point, forming an arm mechanism        to which a mass may be coupled directly or indirectly at a mass        coupling point,

balanced by at least one spring, at one end directly or indirectlyconnected to the arm mechanism at a spring connection point, the otherend directly or indirectly connected to the surroundings at a springbase point,

wherein the spring base point is located substantially on an axis whichextends through the movable pivot point and substantially parallel to adirection of a force exerted on the spring balanced support device atthe mass coupling point due to the force of gravity on the mass, orwherein the spring base point is located at a distance from said axisalong a line which intersects the axis and which extends substantiallyparallel to a pivot point axis of the movable pivot point,

wherein the movable pivot point is movable along the axis in order toadjust the spring balanced support device.

In the spring balanced support devices according to U.S. Pat. No.4,387,876 and U.S. Pat. No. 4,883,249, a spring is provided to balancethe moment generated by the weight of its balanced mass. In thisrespect, the present invention is similar to the devices of U.S. Pat.No. 4,387,876 and U.S. Pat. No. 4,883,249. The known devices comprise anadjusting mechanism for adjusting the device to balance a differentweight. The adjusting device works by adjusting the spring.

In U.S. Pat. No. 4,387,876 and U.S. Pat. No. 4,883,249 severalembodiments are shown. The adjusting mechanism operates on the basis ofadjusting one of the mount positions of the spring. Either the end ofthe spring which is attached to the arm mechanism, or the end of thespring which is attached to the surroundings (i.e. the base) isadjusted. In this way, for any given position of the arm, the momentwhich the spring exerts on the arm, can be adjusted to another constantvalue. In U.S. Pat. No. 4,387,876 the adjustment is carried out by aknob 32 which is used to vary the position of the slider 38 via whichthe spring is connected to the arm mechanism. It is the end of thespring which is attached to the arm mechanism which has an adjustableposition. In U.S. Pat. No. 4,883,249 it is the position of the base endof the spring which is adjustable. For instance in FIG. 9, the element99 can be rotated to vary the height of element 98. FIG. 25 shows asimilar construction.

These devices were found to be suitable only for adjusting for loadshaving relatively small variations in weight. These devices are alsoquite complex to construct and are quite slow in adjusting for adifferent weight, or have other limitations. These devices are forexample not suitable for pick and place operations.

The present invention is different from these constructions in thatadjusting the spring balanced support device is executed by moving apart of the arm mechanism itself, by a translation of the movable pivotpoint. The arm mechanism has no fixed points, all parts of the armmechanism are movable in at least one direction.

Moving the pivot point of the arm mechanism appears counter-intuitivebecause the arm mechanism itself is no longer connected to any fixedpoint in space.

Furthermore, the adjusting of the arm mechanism may influence theposition of the mass. This may be seen as a disadvantage. In anembodiment, the invention provides measures to counteract this tendency.The adjusting of the arm mechanism also changes the range of the armmechanism, which may also be seen as a disadvantage of the invention.This can be counteracted by dimensioning the spring balanced supportdevice properly for the required application.

The invention has a number of advantages. Moving the pivot point of thearm mechanism was found to reduce the construction effort necessary tobuild an adjustable spring balanced support device, allowing a simplerconstruction of both the spring balanced support device and itsadjustment mechanism, requiring less components. Further, the springbalanced support device has a low friction in use. A preferred andsimple embodiment was found in which the adjustment can be executed withzero force in a certain position of the arm mechanism, which is referredto as its “phantomspring” position. This enables a very energy efficientadjustment of the spring balanced support device.

With a simple construction, low friction, and enabling quick adjustmentwith low force necessary for the adjustment, spring balanced supportdevices according to the invention are suitable for various applicationsin different categories of use.

The invention may be used in a broad range of differentapplications/use. Some of the advantages may not be achieved in everyapplication.

One main category of use is a pick and place operation. Typical pick andplace operations may for instance take place in airports where luggageneeds to be transferred from a conveyor belt onto a lorry or vice versa.Other pick and place operations take place in the construction industry,where loads of bricks or bags of cement or other articles need to beloaded or unloaded from a lorry to a building site or where loads needto be positioned, for example without sufficient manpower to hold ormanoeuvre the load. Other kinds of pick and place operations may takeplace along assembly lines. Other pick and place operations occur inlogistical operations, such as package delivery services, and many othersituations. Other types of pick and place operations may take place inother types of businesses, such as newspaper or other printing &publication businesses, where packs of newspapers or magazines need tobe loaded onto a pallet or lorry or crate.

Further kinds of pick & place operations may relate to picking andplacing of people, i.e. picking up of one or more persons, weighing theone or more persons, moving the one or more persons to another locationand placing said persons at said location.

Other applications where the invention can be used for pick and placeoperations may relate to situations where the impact on either thesystem or the load (or both) needs to be reduced or avoided.

Another situation is known from moving vessels that need to be loaded orunloaded, or in other situation where a load is lifted by a crane orother lifting device. In such a situation, it is beneficial for the massto be suspended in a balanced manner instead of in a fixed manner.

Common for many of these situations is that loads of often varying andunknown weight need to picked up at one location, moved to a targetlocation and placed or released at said target location. However, evenif the load is known in advance and is the same for each pick and placeoperation, the picking and placing operation itself results in a varyingload exerted on the spring balanced support system.

The coupling and decoupling of the load with the spring balanced supportdevice are defining moments for the use of the spring balanced supportdevice in this category of application. In this respect, pick & placeoperations are different from applications where the main use is abalanced movement of a mass which stays attached to the spring balancedsupport device.

A pick and place operation according to the invention may work veryintuitively. Because the force for counteracting the force of gravity isprovided by a spring, a drive or actuator is not required for thevertical movement of the mass. This results in at least the upward anddownward movement being performed by muscle power of the operator. Thisresults in a smoother and mostly quicker operation than if a drive oractuator were to be used. However, the invention is not limited toembodiments without a drive or actuator. A drive or actuator could forinstance be used for the horizontal movement of the object, for themovement of the whole spring balanced support device in any direction,or for the adjusting process, as is discussed below.

The invention may also be engaged in a category of applications where itis used mainly for balanced movement of the mass, where no picking orplacing takes place or very little picking and placing takes place, inother words in situations where a load, once engaged with the springbalanced support device, is more or less continuously connected to thespring balanced support device. Sometimes, the load varies onlygradually in time or at certain limited moments in time only. In thesecases the mass, part of the mass or more of the same kind of mass isalmost continuously being connected to the spring balanced supportdevice.

The invention may also be used in another category of applicationswherein the load itself is kept in a stationary position when thesurroundings move. Such a situation is known from measuring devicescarried by a person which need to be kept stable. The measuring devicemay be a camera or a different measuring device. The person moves, butthe measuring device needs to be kept as stable as possible. Yet anotherapplication is in suspension systems in for example the automotiveindustry.

It is implicit to a spring balanced support device that the springbalances the force at the mass coupling point for different angularpositions of the first arm. The axis will generally be vertical, butthis need not be the case. It is also possible that the first directionand the axis extend at a different angle to the horizontal. The axis maybe horizontal.

In an embodiment, the arm mechanism comprises a second arm which ispivotably connected to the first arm at an elbow pivot point (or elbowjoint), wherein the second arm is further coupled to the surroundingsvia a second movable pivot point which is movable substantially parallelto said axis. Generally but not always the second movable pivot pointwill be movable substantially along said axis. The second arm creates apossibility of a simple linear movement of the mass coupling point, i.e.eliminates movements of the mass transverse to the axis. There willstill be considerable forces transverse to the axis, which disadvantagecan be solved as seen explained below. Generally but not always, thearms have substantially the same length, and the elbow pivot point willbe located at the same distance to the axis on both arms. This resultsin the feature that the two movable pivot points are locatedsubstantially at a same distance to the elbow pivot point(s), which isrelevant for an exact zero force adjustment

It was found that the combination of a movable pivot point and amechanism having two arms was very practical, because the constructionfor a linear movement of the mass coupling point can be simply combinedwith the construction for linear movement of the adjusting of the firstmovable pivot point.

In an embodiment, the arm mechanism comprises a second arm which ispivotably connected to the first arm at an elbow pivot point and furthercomprises a third arm and a fourth arm, which are pivotably connectedwith the first and second arm in a substantially parallelogramconfiguration, wherein the fourth arm is connected to the second arm ata second movable pivot point.

The four arms may be connected to one another substantially at theirends. The lower end of the first arm and the upper end of the second armmay define a vertical axis. The second movable pivot point may bemovable along the axis and in a direction transverse to the axis. It isnoted that the axis may also have a different orientation than verticalin which case the lower end need not be a “lower” end. This embodimenthas the benefit that all forces on the axis transverse to the axiscancel each other out.

In a different embodiment, the spring balanced support device comprisesa second arm, connected to the first arm via a pivot connection, thesecond arm having a fixed orientation with respect to the axis and beingmovable substantially along the axis, the pivot connection beingslideable along the first or the second arm. The pivot connection may bearranged in a cam on one of the arms. The second arm will generally beslideably arranged on a carriage.

In an embodiment, the mass is coupled directly or indirectly to the armmechanism at the second movable pivot point.

In an embodiment, the arm mechanism is not connected to any fixed baseand each part of the arm mechanism is movable at least in a directionparallel to said axis, wherein in particular none of the one, two orfour arms of the arm mechanism are directly connected to a fixed base.

The position of the spring connection point may be fixed andnon-adjustable and/or the position of the spring base point may be fixedand non-adjustable. By fixing the ends of the spring, a simpleconstruction is created. This is different from for instance U.S. Pat.No. 4,387,876 and U.S. Pat. No. 4,883,249 wherein either the base end orthe mechanism end of the spring is adjusted.

In an embodiment, the second movable pivot point is operable to bepositioned at a predetermined distance from the spring base point,wherein a change in potential energy of the arm mechanism as a result ofa movement of the first pivot point is substantially the same as achange in spring energy in the least one spring as a result of saidmovement.

During the adjusting process of the first movable pivot point, thesecond movable pivot point is maintained in a certain position at thelevel of the spring base point at the moment of engaging or disengagingof the mass. This results in an adjustment procedure with zero force orsubstantially zero force. The second movable pivot point may bepositioned just offset of the spring base point in order to compensatefor the own weight of the arm mechanism. The second movable pivot pointmay be maintained at substantially the same position by adjusting thespring balanced support device to the changed mass so quickly that thesecond movable pivot point generally does not change in position, by alock of any kind, or by a combination of these two methods.

In an embodiment, the spring balanced support device may furthercomprise a brake device constructed to fixate the second movable pivotpoint during the adjusting step. The brake device may be operatedmanually or be connected to a control device.

The spring balanced support device may further comprise a brake deviceconstructed to alternately:

-   -   during an adjusting step, fixate a position of the mass coupling        point along said axis while allowing a movement of the (first)        movable pivot point along said axis,    -   during a balancing step, fixate the position of the (first)        movable pivot point along said axis while allowing a movement of        the mass coupling point along said axis.

It will be appreciated that the device has two modes, i.e. an adjustmentmode for an adjusting step and a balancing mode for a balancing step.The fixating of the first movable pivot point may be performed by theactuator which also moves the movable pivot point. It will beappreciated that fixating the position of the second movable pivot pointduring the adjusting step may be also done by adjusting very quickly.

If the axis extends vertical, the movable pivot point is situatedessentially vertically underneath the spring base point which bears thespring force, and moves vertically along the axis. It will be understoodthat relatively small deviations of the alignment between the force atthe mass coupling point and the axis disadvantageously affect thebalancing effect of the spring somewhat but fall within the scope of theinvention.

The spring balanced support device may further comprise:

-   -   a weighing device configured to weigh the mass which is        supported by a mass support member,    -   an actuator being constructed to move the movable pivot point,    -   a control device being connected to the weighing device and to        the actuator, wherein the control device is configured to        control the actuator for adjusting the position of the movable        pivot point on the basis of a signal of the weighing device        which is indicative of the measured weight of the mass.

With this embodiment, the adjusting of the spring balanced supportdevice to a new weight can be performed quickly and automatically orsemi-automatically. This allows relatively fast and reliable pick andplace operations.

In a further embodiment, the brake device is also coupled to the controldevice, the control device being configured to fixate the position ofthe mass coupling point along said axis during the weighing of the mass.This allows fast measuring of the weight and adjusting to the new mass.

In an embodiment, the weighing device is coupled directly to a masssupport member which is configured to engage the mass.

In an embodiment, the weighing device comprises a load cell and anaccelerometer, the load cell and accelerometer each being connected tothe control device. The control device is configured to determine theweight of the mass on the basis of the data of the load cell and theaccelerometer. This embodiment allows measuring of the weight withoutholding the mass stationary and increases the operating speed.

In an embodiment, the spring is connected to the arm mechanism at theelbow connection between the first arm and second arm, and—in case of anarm mechanism comprising four arms—the springs are connected to the armmechanism at the respective elbow connections. A connection of thespring at the elbow joint(s) is preferable because it results in anefficient use of the spring force. It also enables zero forceadjustment. A connection of the spring to the second arm will result insome loss of equilibrium at varying positions of the load and willnormally not be preferable option, but falls within the scope of theinvention. The skilled person will understand that the word “springs” incase of a four arm mechanism also comprises a single spring having twosections and extending between both elbow connections via the springbase point.

In an embodiment, the mass coupling point is located substantially onthe axis. The force exerted at the mass coupling point may be alignedwith the axis.

In an embodiment, the spring balanced support device comprises:

-   -   a wagon comprising wheels or skidding members,    -   a frame being connected to said wagon, the frame extending over        a vertical distance,

wherein the arm mechanism and the at least one spring are connected tosaid frame.

The wagon allows great horizontal movements of an object, or allows themovement of the support device to another pick & place location. Thewagon may roll or skid on rails. The rails may extend below or above thewagon as an overhead rail. The support device according to the inventionmay also be mounted otherwise, for example on a free roaming wagon onwheels. The wagon may be self propelled, i.e. be a motorized vehicle,and may be driven on a public road.

In an embodiment, the spring balanced support device comprises atransmission device being mechanically interposed between the mass andthe arm mechanism, the transmission device being configured to cause aratio of a vertical movement of the mass coupling point and a verticalmovement of the mass itself to be less than 1:1.25 or more than 1:0.75.

The transmission device is coupled at an input side thereof to the masssupport member and coupled at an output side to the mass support memberconnection. The transmission device creates an advantage in that thevertical operating range of the mass support member can be increased ordecreased. The transmission device may comprise a pair of pulleys havinga different diameter or gears or have a different suitable form. Asingle pulley having two different diameters or a scissor mechanism areother possibilities for the transmission device and other options forthe transmission device are conceivable.

If the ratio is greater than 1:0.75, very precise vertical movements ofthe object are possible in a limited range.

In an embodiment, the spring balanced support device comprises aprotruding arm which is connected directly or indirectly to the armmechanism, wherein the protruding arm extends over a horizontaldistance, wherein the protruding arm is connected to a carriage which isguided by a rail which extends parallel to said axis. The rail andcarriage bear the moment caused by the weight multiplied by the lengthof the arm. In particular, the rail may be fixed to the frame, so thatthe protruding arm is coupled to the frame via the carriage which isguided by the rail and arranged to move parallel to said axis relativeto said frame.

In an embodiment, the protruding arm is connected directly or indirectlyto the arm mechanism via a hinge having a vertical axis. The hingeallows the arm to pivot, creating an operating range about the verticalaxis.

The protruding arm may be segmented and comprise a first arm part and asecond arm part being coupled to one another via a sliding or rollingdevice, the second arm part being movable in a horizontal directionrelative to the first arm part. The segmented arm allows relativelyhigh-precision horizontal movements of the object without needing tomove the arm mechanism in a horizontal direction. More segments are alsopossible.

In an embodiment, the spring balanced support device further comprises apulley device comprising an upper pulley, a lower pulley and an endlessflexible member being supported by the upper and lower pulley andextending at least in part parallel to said rail, wherein the carriageis connected to said endless flexible member. The mass support member isindirectly coupled to the arm mechanism via the pulley device. Thepulley device may comprise a lock. This has the benefit of a safeguiding of the mass support member via the carriage and a rail. A brakedevice may be provided which brakes the endless loop in both directions.Undesired, sudden movements may advantageously be prevented with thelock. The rail generally extends vertically.

In an embodiment, the at least one spring is attached to a fixed springbase via the spring base point wherein the fixed base and the at leastone spring are located at a distance from the operating range of the armmechanism, for instance outside a region which is defined by the rangeof operation of the first movable pivot point and the range of operationof the second movable pivot point or at a distance from a plane definedby the first arm and the axis. For some applications the region may bemore particularly defined by a first plane oriented at a right angle tothe axis and extending through the end of the range of the first movablepivot point and a second plane oriented at a right angle to the axis andextending through the end of the range of the second movable pivotpoint. For other applications the at least one spring may be locatedvery close to the operating range of the arm mechanism, but not withinthe operating range by placing it right next to it in another plane,i.e. at a distance from a plane defined by the first arm and the axis.

A position of the springs which is remote from the position of the armmechanism has several benefits. It does not require the use of zerolength springs, and it allows the arm mechanism and the springs to bepositioned where the space is most optimal. For instance, when the armconstruction is provided in a movable frame, the movable frame beingsupported by a wagon which rolls on wheels, the arm mechanism itself canbe positioned relatively high, above the operator and out of the way ofthe objects which are to be picked and placed. The at least one springmay be located below the lower end of the first arm. The remote locationof the spring(s) allows long springs to be used, which creates arelatively constant force over a substantial range.

In an embodiment, the spring balanced support device according to any ofthe preceding comprises a hand grip directly or indirectly connected tothe first movable pivot point for manually adjusting the position ofsaid first movable pivot point and/or comprising an actuator which ismanually operable, i.e. without a control device. The hand grip allowssimple adjusting of the spring force.

In an embodiment, the brake device may comprise one or more of thefollowing brake members:

-   -   1) a first brake member for braking a vertical movement of the        mass, and    -   2) a second brake member for braking a horizontal movement of        the second protruding arm segment relative to the first        protruding arm segment, and    -   3) a third brake member for braking the pivoting movement of the        arm about pivot axis,    -   4) a fourth brake member for braking a pivoting movement of the        object support member.

wherein the one or more brake members are connected to the controldevice via communication lines, the control device being configured toswitch the one or more brake members on or off, all together or in aparticular sequence

The present invention further relates to a method of supporting a mass,the method comprising

-   -   providing a spring balanced support device comprising at least        one arm, connected to its surroundings via a movable pivot        point, forming an arm mechanism to which a mass may be coupled        directly or indirectly at a mass coupling point,        -   balanced by at least one spring, at one end directly or            indirectly connected to the arm mechanism at a spring            connection point, the other end directly or indirectly            connected to the surroundings at a spring base point,        -   wherein the spring base point is located substantially on an            axis which extends through the movable pivot point and            substantially parallel to a direction of a force exerted on            the spring balanced support device at the mass coupling            point due to the force of gravity on the mass, or wherein            the spring base point is located at a distance from said            axis along a line which intersects the axis and which            extends substantially parallel to a pivot point axis of the            movable pivot point,        -   wherein the movable pivot point is movable along the axis in            order to adjust the spring balanced support device,

the method further comprising:

-   -   engaging the mass with the spring balanced support device,    -   adjusting the position of the first movable pivot point so that        the spring balanced support device generates a spring force        which balances the weight of the mass, and    -   moving the mass relative to the spring balanced support device.

The method provides the same advantages as the device. It is noted thatthe mass may be moved with the spring balanced support device, but it isalso possible to keep the mass still and let the spring balanced supportdevice move. This may arise in the carrying of a measuring device by ahuman or the use of the invention on board a moving vessel for providinga stationary position for the mass. Other applications are alsoconceivable.

In an embodiment, the method comprises disengaging said mass from thespring balanced support device after the moving of the mass relative tothe spring balanced support device.

In an embodiment, the method comprises repeatedly engaging anddisengaging a mass with the spring balanced support device, wherein ateach moment of engaging and disengaging, the mass coupling point has asubstantially same position.

The device according to the invention has a position in which anadjustment with zero force is possible. By each time engaging the masswith the spring balanced device at said zero force position, referred toas its “phantomspring” position, little energy is required for theadjustment process.

In an embodiment of the method, the arm mechanism comprises at least asecond arm which is pivotably connected to the first arm at an elbowpivot point, wherein the second arm is further coupled to thesurroundings via a second movable pivot point which is movablesubstantially along said axis, wherein the spring base point is locatedsubstantially along said axis and within an operating range of thesecond movable pivot point along said axis, the method comprisingengaging or disengaging the mass by the spring balanced support devicein a position wherein the second movable pivot point is positioned at ornear the position of the spring base point along said axis, in whichposition a change in potential energy of the arm mechanism as a resultof the moving of the first movable pivot point is substantially the sameas a change in spring energy in the at least one spring.

The second movable pivot point and the spring base point may be slightlyoffset in order to compensate for the own weight of the arm mechanism.

These positions of the second movable pivot point and the spring baseaxis enable an adjusting step with zero force. The length of the springchanges relatively little and essentially only enough to compensate forthe change in potential energy of the arms. In this position, the firstmovable pivot point can be moved without exerting any force or with verylittle force. This is a very efficient way of adjusting the device. Ifdone repeatedly, the advantage may also be achieved repeatedly.

In an embodiment of the method, the spring balanced support devicefurther comprises an adjustment device comprising:

-   -   a weighing device configured to weigh the mass which is        supported by the spring balanced support device,    -   an actuator being constructed to move the movable pivot point,    -   a control device being connected to the weighing device and to        the actuator, wherein the control device is configured to        control the actuator for adjusting the position of the movable        pivot point on the basis of a signal of the weighing device        which is indicative of the measured weight of the mass,

the method comprising weighing the mass with the weighing device andautomatically adjusting the movable pivot point with the actuator on thebasis of a signal generated by the control device, the signal beingindicative of the weight of the mass. This method allows relatively highspeed pick and place operations.

The spring balanced support device may further comprise a manualadjusting device configured for manually adjusting the first movablepivot point. The manual adjustment device may be provided in addition tothe actuator or as an alternative.

In an embodiment, the spring balanced support device further comprises abrake device constructed to fixate the mass in a vertical direction, thebrake device being coupled to the control device, wherein the controldevice is configured to fixate the vertical position of the mass supportmember during the weighing of the mass, the method comprising fixatingthe vertical position of the mass with the brake device during theweighing of the mass.

In a different aspect, the present invention relates to a springbalanced support device comprising:

-   -   an arm mechanism comprising at least a first arm, wherein the        arm mechanism is connected to the surroundings via a first pivot        point,    -   a mass support member constructed for supporting the mass, the        mass support member being coupled directly or indirectly to the        arm mechanism, and in use exerting a weight force in a first        direction on the arm mechanism due to a weight of the mass,    -   at least one spring, at one end directly or indirectly connected        to the arm mechanism at a spring connection point, the other end        directly or indirectly connected to the surroundings at a spring        base point, the spring being configured to exert a spring        force (F) on the arm mechanism which counteracts the weight of        the mass, wherein the first pivot point and the spring base        point define an axis which is substantially parallel with the        first direction,    -   an adjustment device configured to adjust the magnitude of the        spring force for a given position of the mass support member, in        order to allow a balanced support for different masses having        different weights, wherein the adjustment device comprises:        -   a weighing device configured to weigh the mass which is            supported by the mass support member,        -   an actuator being constructed to move the pivot point, the            spring base point, and/or the spring connection point,        -   a control device being connected to the weighing device and            to the actuator, wherein the control device is configured to            control the actuator for adjusting the position of the pivot            point, the spring base point, and/or the spring connection            point on the basis of a signal of the weighing device which            is indicative of the measured weight of the mass.

With the invention, fast and reliable pick and place operations can becarried out. Surprisingly, it was found that the combination of theweighing device, actuator and control device can be combined with thefeature of the adjustment device which is configured to adjust aposition of the first pivot point, but may also be applied independentlyfrom this aspect. The actuator may be connected to the spring support orto the spring base point, and/or the spring connection point, in orderto adjust the force. This creates a possibility of creating a springbalanced support devices which is derived from the devices disclosed inU.S. Pat. No. 4,387,876 and U.S. Pat. No. 4,883,249, but has an extraquality of being much more suitable for pick and place operations.

The spring balanced support device may comprise a brake deviceconstructed to fixate the mass support member in a vertical direction,the brake device being coupled to the control device, the methodcomprising fixating the mass support member with the brake device duringthe weighing of the mass. This brake device is not necessary when theadjustment is executed very quickly, before the mass support memberchanges its position. This quick adjustment is preferably done in the“phantomspring” position of the spring balanced support device, becausethere the adjustment requires zero force.

The spring balanced support may comprise any of the features accordingto claims 2-25.

The present invention further relates to a method of performing apick-and-place operation, the method comprising:

-   -   providing a spring balanced support device comprising:        -   an arm mechanism comprising at least a first arm, wherein            the arm mechanism is connected to the surroundings via a            first pivot point,        -   a mass support member constructed for supporting the mass,            the mass support member being coupled directly or indirectly            to the arm mechanism, and in use exerting a weight force in            a first direction on the arm mechanism due to a weight of            the mass,        -   at least one spring, at one end directly or indirectly            connected to the arm mechanism at a spring connection point,            the other end directly or indirectly connected to the            surroundings at a spring base point, the spring being            configured to exert a spring force (F) on the arm mechanism            which counteracts the weight of the mass, wherein the first            pivot point and the spring base point define an axis which            is substantially parallel with the first direction,        -   an adjustment device configured to adjust the magnitude of            the spring force for a given position of the mass support            member, in order to allow a balanced support for different            masses having different weights, wherein the adjustment            device comprises:            -   a weighing device configured to weigh the mass which is                supported by the mass support member,            -   an actuator being constructed to move the pivot point,                the spring base point, and/or the spring connection                point,            -   a control device being connected to the weighing device                and to the actuator, wherein the control device is                configured to control the actuator for adjusting the                position of the pivot point, the spring base point,                and/or the spring connection point on the basis of a                signal of the weighing device which is indicative of the                measured weight of the mass.

the method comprising:

-   -   engaging a mass with the mass support member,    -   weighing the mass with the weighing device and automatically        adjusting the magnitude of the spring force with the actuator on        the basis of a signal generated by the control device, the        signal being indicative of the weight of the mass,    -   moving said mass relative to the spring balanced support device.

The method provides substantially the same advantages as the deviceaccording to this aspect of the invention.

In an embodiment of the method, the spring balanced support devicefurther comprises a brake device constructed to fixate at least the masssupport member, the brake device being coupled to the control device,wherein the control device is configured to fixate the position of themass support member during the weighing of the mass, the methodcomprising fixating the position of the mass support member in thevertical direction with the brake device during the weighing of themass.

The method provides substantially the same advantages as the deviceaccording to this aspect of the invention.

LIST OF FIGURES

Below, the invention will be explained in more detail by means ofexemplary, non-limiting embodiments and with reference to the figures.Like reference numerals denote like parts.

FIG. 1 shows a schematic side view of a spring balanced support deviceaccording to the prior art.

FIG. 2A shows a schematic side view of a first embodiment according tothe invention.

FIG. 2B shows a schematic side view of a second embodiment according tothe invention.

FIG. 2C shows a schematic side view of a third embodiment according tothe invention.

FIG. 2D shows a schematic side view of a fourth embodiment according tothe invention.

FIG. 3A shows a schematic side view of a fifth embodiment according tothe invention.

FIG. 3B shows a schematic side view of a sixth embodiment according tothe invention.

FIG. 3C shows a schematic side view of a seventh embodiment according tothe invention.

FIG. 3D shows a schematic side view of an eighth embodiment according tothe invention.

FIG. 3E shows a schematic isometric view of a ninth embodiment accordingto the invention.

FIG. 4A shows a schematic side view of a tenth embodiment according tothe invention.

FIG. 4B shows a schematic side view of another embodiment according tothe invention.

FIGS. 5A and 5B show an isometric view of yet another embodiment of theinvention in use.

FIG. 6A shows a schematic side view of an embodiment according to afurther aspect of the invention.

FIG. 6B shows a schematic side view of another embodiment according tothe further aspect of the invention.

DETAILED DESCRIPTION OF THE FIGURES

Turning to FIG. 1, a spring balanced support device 1 according to theprior art is shown. The spring balanced support device comprises an arm2, a spring 3, a pivot point 4 which supports a lower end of the arm 2,and a movable base 5 which is configured to adjust the length of thespring for a given position of the arm 2. A further adjustment mechanismis provided via a slider member 8.

The spring balanced support device 1 is configured to support an object12. If the object is heavy, the movable base 5 is moved upwards and/orthe slider 8 is adjusted towards the end of the arm to increase themoment generated by the spring around the pivot point 4.

The device of FIG. 1 is indicative of the solutions provided by U.S.Pat. No. 4,387,876 and U.S. Pat. No. 4,883,249. When considering themoments about pivot 4, it can be found that both the moment of the load12 and the counteracting moment of the spring 3 about pivot 4 vary withsin β, which results in a perfect equilibrium for all angles β. This isthe general principle of spring balanced support devices.

One of the disadvantages of these devices is that pick and placeoperations are difficult to carry out due to the varying weight. In thepresent invention, a further insight was developed in that an adjustablespring is in practice quite difficult to construct. This makes thedevices of U.S. Pat. No. 4,387,876 and U.S. Pat. No. 4,883,249 quitecomplex and cumbersome, when put to practice.

Turning to FIG. 2A, a first embodiment of the spring balanced supportdevice 10 according to the invention is shown. The arm mechanism 14comprises a single arm 21. The end 29 of the first arm 21 is pivotablyconnected to a movable pivot point 76 mounted on a movable base 42. Thefirst arm 21 pivots about a pivot point axis 77 extending through themovable pivot point 76. The movable base 42 is movable in a verticaldirection and is fixed in a horizontal direction by a guide or rail 43.

A spring 36 is connected to the arm mechanism 14 at a fixed springconnection point 27 at a mechanism end 40 of the spring. The spring isfurther connected at its upper end 38 to a spring base point 52 mountedon a fixed base 50. During rotation of the first arm 21, the springpivots about a spring base axis 51 which extends through the spring basepoint 52. The spring base axis 51 intersects axis 17 and extendsparallel to the pivot point axis 77. The spring base axis 51 is alsoindicated as line 51.

The mass (or object) 12 is connected to the arm at a mass coupling point200. A force of gravity on the mass is directed along a first direction71.

An axis 17 extends through the movable pivot point 76 and extendssubstantially parallel to a direction 71 of the force exerted at themass coupling point 200. The axis 17 extends transverse to the springbase axis 51. Generally, the axis 17 will extend through the spring basepoint 52. However, the spring base point 52 may be positioned before orbehind the plane of drawing in FIG. 2A. In that case, the axis 17extends through the spring base axis 51 about which the spring rotates,but not through the spring base point 52 itself. The spring base axis 51is substantially parallel to the pivot point axis 77 of the movablepivot point 76. In this case, the spring base point 52 is located at adistance from the axis 17, along the line 51 which extends parallel tothe pivot point axis 77. The movable pivot point 76 is movable in adirection 46 which is substantially aligned with the axis 17 andsubstantially aligned with the first direction 71. The arm 21 extends atan angle β to the axis 17.

In use, the position of the movable pivot point 76 can be adjusted tobalance the spring force to the weight of the mass 12.

FIG. 2A is schematic. A frame may be provided which interconnects rail43 and fixed base 50. The movable pivot point 76 is movable relative tosaid frame and relative to said rail 43.

Turning to FIG. 2B, an embodiment of the spring balanced support device10 is shown which supports an object 12. The spring balanced supportdevice comprises an arm mechanism 14. The arm mechanism comprises afirst arm 21 and a second arm 22. The arms 21, 22, are interconnectedvia an elbow pivot connection 26 at their ends 28. The arms 21, 22extend at an angle gamma (γ) to one another. The arms 21 and 22 willgenerally be of substantially equal length, and the distance from theelbow point to the axis along both arms will generally be equal.

The spring is connected to the first arm but may be connected to thesecond arm or to the hinge connection 26 between the two arms. Thespring may also be indirectly coupled to the arm mechanism. The spring36 extends at an angle α to the axis 17. The fixed base 50 is fixed inspace. It will be seen in a further embodiment that the spring balancedsupport device as a whole, including fixed base 50, can be arranged on aframe which is movable in any direction including the horizontaldirection.

The movable pivot point 76 is positioned vertically underneath thespring base point 52. The spring base point is located along axis 17,but is not in the way of the second movable pivot point 25. This can bearranged in various manners for instance by placing the spring basepoint out of the plane of drawing. The second movable pivot point 25 hasan operating range and the spring base point 52 is located near, orwithin the operating range of the second movable pivot point 25. Movablepivot point 25 is movable substantially parallel to the axis. Generally,but not always, movable pivot point 25 is movable substantially alongthe axis.

At an upper end 19 of the second arm 22, the arm 22 is pivotablyconnected to a movable support 61 via a (second) movable pivotconnection 25. The movable support 61 is a movable carriage which ismovable in a vertical direction but fixed in a horizontal direction by arail 62. A mass support member 18 is connected to the movable support61, which mass support member supports the object 12. The mass supportmember 18 comprises an arm 60 which protrudes horizontally. The arm 60is rigidly coupled to the movable support 61 and the movable support 61maintains the arm in its working orientation, which in this case ishorizontal. The connection between the mass support member 18 and thearm mechanism 14 is referred to as the mass coupling point 200. Themovable pivot connection 25 coincides with the mass coupling point 200and may in practice also coincide with mass support member 18.

The weight force is transferred to the arm mechanism at the masscoupling point 200 and is directed in the direction 71. In FIG. 2B thisfirst direction 71 is vertical.

The mass support member 18 is not coupled to the arm mechanism 14directly, but via the carriage 61 which is guided by the vertical rail62. It is the carriage 61 which is connected to the arm mechanism 14.The carriage is held in a fixed orientation by the rail 62, and bendingmoments resulting from the weight of the object 12 multiplied by thelength of the horizontal arm 60 are transferred by the carriage 61 ontothe rail 62. The carriage and the rail are constructed to maintain theprotruding arm in an operable orientation. Only a short length of rail62 is indicated, but the skilled person will understand that the rail 62extends over the whole operating range. The same applies for the rail43, which extends over the whole adjustment range.

A brake device 126 is provided to lock the movable support 61 at themoment of adjusting the position of movable base 42. The brake device126 may comprise a first brake member 127 configured to brake the wheels79 of the movable support 61. The brake device may be coupled to thecontrol device 72.

Each part of the arm mechanism 14 is movable at least in a directionparallel with the axis 17, i.e. there is no part of the arm mechanismwhich is fixed to the surroundings.

A weighing device 16 is provided between the object 12 and the armmechanism 14 to weigh the object. The weighing device may also have adifferent position. An adjusting device 44 comprising an actuator 45 isprovided to move the movable base 42 in a vertical direction 46. Theactuator may be electric, pneumatic or hydraulic or otherwise. Thespring balanced device 10 further comprises a control device 72 which isconnected via connection lines 73, 74 to respectively the weighingdevice 16 and the actuator 45 of the adjustment mechanism. The actuator45 is also capable of acting as a brake and fixating the position of themovable pivot point 76 during the moving mode in which the device isbalancing the mass.

In use, the object is weighed and a signal indicating the weight is sentto the control device via line 73. The control device 72 determines asignal to be sent to the actuator and sends the signal via the line 74.The actuator 44 adjusts the position of the movable base 42. Theweighing and adjusting operation can take automatically orsemi-automatically. In a short period of time, for instance less than asecond, the springs 36, 37 balance the weight of the object 12 and theobject may be picked up and placed.

It is noted that when the position of the movable base 42 is adjustedwith the adjusting mechanism 44, the position of the mass support member18 may change in an undesired way. This can be prevented with, forexample, the brake device 127.

The mass support member 18 can also comprise a platform which supportsthe object or a hook which is attached to the object. The mass supportmember 18 can also have a different form, for instance an eye or still adifferent form.

In another embodiment, the weighing device 16 has a visual indicator andthere is no control device 72. The movable base can be adjustedmanually. The adjustment is performed manually by the operator on thebasis of the measured weight. It is also possible that no weighingdevice is present, in case objects of a known weight need to be pickedand placed or in case no picking and placing is required, i.e. when anobject only needs to be moved, but not frequently coupled to anduncoupled from the mass support member.

Turning to FIG. 2C, an alternative variant is shown in which the secondarm 22 is rigidly connected to the movable support 61 and is fixed in agiven orientation which may be horizontal, and wherein the first arm 21and second arm 22 are connected to one another via a sliding slot 120and a cam which slides through the sliding slot 120. The connectionbetween the first and second arm not only allows a pivoting movement,but also a sliding movement. This embodiment can also be executed withthe sliding slot on first arm 21 instead of the second arm 22.

Turning to FIG. 2D, the variant of FIG. 3C is shown including a controldevice 72 which is connected to a weighing device 16 and an adjustmentdevice 44 having an actuator. This allows automatic adjustment. In thisembodiment the mass is coupled to the second arm, which has the benefitit does not move in a direction transverse to the axis 17.

Turning to FIG. 3A, the embodiment of FIG. 2B is shown, but having ahand grip 145 instead of a control device 72. The hand grip 145 may alsobe provided in addition to the control device 72.

The arm mechanism 14 has its elbow pivot point 26 located substantiallyon the same position as the spring connection point 27. Points 25, 76and 52 are all located substantially on the axis 17 (when viewed in adirection parallel to the pivot point axis 77). The elbow pivot point 26is located at a same distance from the two movable pivot points 25 and76. The movable pivots points 76, 25 have their operating ranges chosensuch that point 25 can be positioned near or at the position of point52. Generally, point 76 will be on the same side of point 52 on the axisas point 25. In addition to being movable substantially along the axis,the two movable pivot points 25 and 76 are also enabled to be maintainedat a certain position along said axis.

In this configuration the arm mechanism may be regarded as reversible,or direction invariant as seen from one direction on the axis 17 or theother. An arm mechanism 14 in this configuration can be regarded asmirrored in line 75 which extends through elbow pivot point 26,transverse to the axis 17. Both the first pivot point 76 and the secondmovable pivot point 25 can be moved along the axis:

-   -   During adjusting mode, the second movable pivot point 25 is held        in position and named “passive”, while the first movable pivot        point 76 is being able to move for adjustment, and named        “active”.    -   During balancing mode, this is reversed, i.e. the second movable        pivot point 25 is moved and named active, being actively        balanced, while the first movable pivot point 76 is stationary        and named “passive”.

The second movable pivot connection 25 is positioned near the level ofthe spring base point 52, at a certain distance (300). It is noted thatthe second movable pivot connection 25 is positioned slightly below thespring base point 52. This offset compensates for the mass of the armmechanism 14 itself. The distance 300 between the second movable pivotpoint 25 and the spring base point 52 depends on the weight of the armmechanism 14. Distance 300 is the referred to as the “phantomspring”distance, when the moment generated by the spring 36 around pivot point25 only changes in order to compensate for a change in potential energyof the arm mechanism itself during adjusting mode. This implies that theadjusting process can be carried out with very little force or withoutany force, and is referred to as zero force adjusting. This provides asubstantial advantage.

Maintaining pivot points 25 and 76 at their respective requiredpositions can be executed in various ways, among others using a brake126, and/or by adjusting the spring balanced support device 10 veryquickly or substantially instantly at the moment at which the weight ofthe mass 12 exerted on the spring balanced support device 10 changes.

Adjustment by translating pivot point 76 may also be executed in variousways, such as manually, passively mechanical (for instance by using asecond spring), or actively mechanical for instance by using a motor oractuator 45. Such a motor or actuator can also function as a lock so aseparate brake 126 may not be necessary.

Enabling zero force adjustment in such a relatively simple embodimenthas several advantages compared to known spring balanced supportdevices.

Turning to FIG. 3B, an embodiment is shown which is similar to theembodiment of FIG. 2B, but wherein the axis 17 is rotated over 90degrees and extends horizontally. The mass is suspended from member 18,which is a cable guided over pulley 140.

The figure shows the spring balanced support device can be mounted inany conceivable orientation. The direction of gravity does not need tobe parallel to the axis 17. The skilled person will understand that theaxis 17 and the first direction 71 can also be oriented at a differentangle, as long as they are substantially parallel. The embodiment ofFIG. 3B does not work completely the same as the embodiment of FIG. 2B,because the weights of the components of the arm mechanism 14 itself arenot aligned with the axis 17, which results in a slight deviation.

In this figure the direction of gravity is square/transverse to theaxis. However, by use of a pulley 140, the direction of the force ofgravity on the mass exerted on the spring balanced support device insecond movable pivot point 25 is aligned with the axis 17. For accuratebalancing, the direction of the force exerted on the spring balancedsupport device by the gravity force on the mass needs to besubstantially parallel to the direction of the axis 17 extending throughthe spring base point 52.

At certain angles of the axis 17 to the direction of gravity, the springbalanced support device needs to be properly designed to compensate fordifferent gravity forces on the arm mechanism itself. In some cases itis preferred to rotate the arm mechanism 14 to an orientation whereinthe arm mechanism is moving substantially in a horizontal plane.

Turning to FIG. 3C, another embodiment of the spring balanced supportdevice 10 is shown.

The figure shows a spring balanced support device according to theinvention where the arm mechanism from the preceding FIGS. 2B, 3A and3B) is executed twice, mirrored in the axis 17. In this embodiment, theforces from the left upper and lower arms 23 and 24 in pivot points 76and 25 are cancelled out by opposite forces from the right arm parts 21and 22. This embodiment has substantially the same benefits as theembodiments as shown in the said preceding figures. It has twoadditional benefits: rails 43 and 62 can be constructed very lightlybecause forces in the x-axis are limited, and the balanced movement ofpivot point 25 need not be limited to movement along axis 17. In otherwords: pivot point 25 does not need to be restricted for movementsubstantially along attached to rail 62 but may also move away from axis17 and toward axis 17.

The spring balanced support device 10 comprises an arm mechanism 14. Thearm mechanism comprises a first arm 21, a second arm 22, a third arm 23and a fourth arm 24. The four arms 21, 22, 23, 24 are interconnected viapivot connections 26, 76, 25 at their ends 19, 28, 29. The four armsform a parallelogram configuration having four corners, i.e. an uppercorner 31, a right corner 32, a lower corner 33 and a left corner 34. Ifthe axis has a different orientation, the words “upper” and “lower” donot apply, but they are used here for reasons of simplicity.

The left and right pivot connections 26 are also indicated as the elbowjoints 26. The right and left corners 32, 34 are also indicated as theelbows. The first arm is also indicated as the lower right arm 21, thesecond arm is also indicated as the upper right arm 22, the third arm isalso indicated as the lower left arm 23 and the fourth arm is alsoindicated as the upper right arm 24.

A mass support member 18 in the form of an arm is provided whichsupports the object 12.

The spring balanced support device comprises a first spring 36 and asecond spring 37. The springs 36, 37 extend at an angle 2*α to oneanother. The first and second spring are connected at their upper ends38 resp. 39 to a spring base point 52 in the form of a fixed base 50. Itwill be seen in FIG. 4B that the springs may also be guided around thespring base point 52 to a fixed base 50 which is provided underneath thespring base point 52 and be connected to said fixed base with theirlower ends. The springs 36, 37 exert an upward force on the armmechanism. The fixed base 50 is fixed in space. It will be seen withrespect to FIG. 4A that the fixed base 50 can be arranged on a frame 84which is movable in a horizontal direction. Therefore, “fixed base” inthis respect should be interpreted purposively and does not excludehorizontal or vertical movements of the spring balanced support deviceas a whole. The first movable pivot point 76 is positioned verticallyunderneath the spring base point 52.

The opposite ends 40, 41 of the springs are connected to the armmechanism 14 at respective spring connection points 27 which are locatedon the first and third arms 21, 23. The springs may also be connected tothe elbows. It is also possible that the respective springs 36, 37 areconnected to the respective first arm 21 and third arm 23 at a differentposition along the length of said arms.

A weighing device 16 is provided between the object 12 and the armmechanism 14 to weigh the object. The weighing device may also have adifferent position.

The first movable pivot point 76 is provided at the bottom corner 33.The ends 29 of the right arm 21 and left arm 23 are pivotably connectedto one another and pivotably connected to the movable base 42. Themovable base 42 may be guided along a rail 43 which extends vertically.The rail 43 allows a vertical movement of the movable base 42 but not ahorizontal movement of the movable base 42. An adjusting device 44comprising an actuator 45 is provided to move the movable base in avertical direction.

A vertical axis 17 is defined which extends through the fixed base 50and the movable base 42. The vertical axis may also extend through theupper corner 31. The fixed base 50 and the movable base 42 are locatedat a base distance 47 from one another. The adjusting device 44 isconstructed to change the base distance 47. The upper corner 31 andlower corner 33 are located at an arm distance 49 from one another.

The upper corner 31 may also be guided along a vertical rail 62 in orderto prevent any horizontal movement of the upper corner 31 and of themass support member 18.

The right upper arm 22 and the right lower arm 21 make an angle γ withone another. Likewise, the left upper arm 24 and the left lower arm 23make an angle γ with one another.

The arm mechanism 14 has the feature that when the mass support member18 is moved downward, the spring connection points 27 are forcedoutwardly away from each other, and a distance 59 (shown in the rightside in FIG. 3) between the spring connection points 27 and the springbase point 52 is increased. This results in an increase in the springforce F.

As in the devices of the prior art, it can be found that as long as theaxis 17 which is defined by the spring base point 52 and the pivot point76 of the movable base extends parallel to the direction 71 of theweight force on the arm mechanism, the moments of the load 12 and thesprings 36, 37 about the movable pivot point 25 of the movable base varywith sin β, allowing a perfect equilibrium, i.e. a spring balancedmechanism.

In operation, an object 12 is suspended from the mass support member 18.The object is weighed with the weighing device 16. The adjusting device44 is operated to move the movable base 42 in a vertical direction, seearrow 46. By moving the lower corner 33 in a vertical direction, thesprings 36, 37 are either extended or shortened. A spring force F varieswith the lengthening or shortening of the springs 36, 37.

In this way, the weight of the object 12 can be balanced by the combinedspring force F of the springs 36, 37. In other words, the verticalcomponents of the forces exerted by the two upper arms 22, 24 on themovable pivot point 25 of the upper corner 31 counteract the weight ofthe object 12 when the moveable base 42 is in the correct position. Itis noted that by extending or shortening the springs, a certain amountof energy is brought into the system or released from the system. Whenthe second movable pivot point 25 is located near the spring base point52, the adjustment can be carried out with little or no force. In thisway, the amount of energy in the system stays substantially the sameduring the adjustment process.

In practice, use can be made of this feature when it is possible to havea fixed location where the objects are engaged with the spring balancedsupport device. For instance, when objects have to be picked up from asame platform or belt conveyor each time, the spring balanced supportdevice can be configured such that when the object support member is inthe engagement location, the second movable pivot point 25 is near thespring base point 52, at its phantomspring distance, where theadjustment can be done with zero force. The same concepts as mentionedin the description of FIG. 3A apply

Once the weight of the object is balanced, the object can be movedmanually in a vertical direction with very little force. Even arelatively heavy object can be moved with little force. During themovement of the object 12, the position of the movable base 42 is heldstationary, i.e. the position of the movable base 42 is only movedduring the process of adjusting the spring balanced support device to anew weight.

Since the movable pivot point 76 is adjustable, the spring balancedsupport device can be adjusted to varying weights. The range of weightsthat can be handled has an upper limit and a lower limit. The upperlimit and lower limits can be varied according to prevailing conditionsin the field of use. When the object is attached to the mass supportmember 18, the weighing process starts. When the weight is determined,the adjustment device 44 is adjusted to the measured weight. This can bedone by hand or automatically. Next, a pick and place operation in avertical direction can be carried out on the object. The verticalmovement is indicated by arrow 48.

It is also possible that the weight of the objects is known in advance.In such a case, the spring balanced support device may be carried outwithout a weighing device. The adjustment device 44 is then adjusted tothe known weight without weighing the objects. Examples are standardsize bricks or stones of which the weight is known, or standard sizecement bags, etc.

Turning to FIG. 3D, an embodiment is shown having a manual adjustingdevice 145. The adjusting device has the form of a hand grip. With thehand grip, the operator can simply move the movable base 42 up or down.The manual adjusting device 44 is coupled to the movable pivot point 76via a “zero force device” 150. The zero force device comprises a secondarm mechanism 151 which is may be in the form of a four arm diamondconfiguration. A lower corner 154 of the second arm mechanism 151 isconnected to a fixed base 152. The hand grip is not connected to fixedbase but only to the movable base 42. A spring 156 is connected withinthe second arm mechanism. The spring 156 extends between the left elbow158 and right elbow 159.

The adjusting device comprises a hand grip 145. With the hand grip, theoperator can simply move the movable base 42 up or down. The hand grip145 is connected to the movable base 142 via a rod. When the movablebase 42 is moved downwards, springs 36, 37 shorten, which releasesenergy and therefore provides a force. At the same time, spring 156extends, which costs energy, and therefore requires a force. The forcesmay cancel each other out so that the adjusting process does not requireany force.

Turning to FIG. 3E, the pivot point axis 77 and the axis 51 through thespring base point 52 are shown. In this embodiment, the second movablepivot point moves along an axis 160 which is not aligned with the axis17 but located at a distance from said axis 17. The arm 22 pivots aboutaxis 162 extending through the second movable pivot point 25. The arm 22is located at a distance from arm 21 by a spacer element 164.

This embodiment allows the second movable pivot point 25 and the springbase point to pass one another.

In another embodiment, the spring base point 52 may be located at adistance from axis 17 along the line 51. In that case, the axis 160 canbe aligned with axis 17 and the second movable pivot point 25 and thespring base point 52 would still be able to pass one another.

Turning to FIG. 4A a further embodiment is shown. The spring balancedsupport device 10 comprises an overhead rail 80 and a wagon 82 whichcomprises wheels 83 and is movable in a horizontal direction 86 alongsaid rail 80. An upper rail 80 and a lower rail 80 are provided tofixate the wagon between the rails 80. A vertical frame 84 or verticalarm 84 is suspended from the wagon 82 and fixed to said wagon. Momentsfrom the frame 84 can be transferred to the rail 80 via the wagon 82.

The embodiment has two arms 21, 22, i.e. a lower arm 21 and an upper arm22. The embodiment has a single elbow and a single spring 36. It isnoted that the single spring 36 may be replaced by two or more springs,for instance parallel springs, if needed. It is also possible todistribute the force of a single spring over a left side and a rightside of an arm mechanism.

A rail 43 is provided which extends vertically and guides both themovable base 42 and the mass coupling point 200 at the end 19 of theupper arm 22. The upper end 28 of the upper arm 22 is held in a fixedhorizontal position by the rail 43.

The horizontal arm 60 comprises a first segment 66 and a second segment68 which are slideably arranged relative to one another via a sliding orrolling mechanism 67. This configuration allows a horizontal movement ofthe object which is indicated by arrow 70. The horizontal movement andthe vertical movement together allow a movement in two dimensions withlittle effort. The mass support member 18 is a platform on which theobject 12 may rest.

The carriage 61 further comprises a hinge 110 having a vertical axis112. The hinge 110 allows rotation of the horizontal arm 60 about thevertical axis 112, thereby allowing a movement of the object 12 in threedimensions.

Turning to FIG. 4B, another embodiment is shown. The arm mechanism 14comprises four arms 21, 22, 23, 24. The frame 84 houses the armmechanism 14. The springs 36 and 37 are located below the arm mechanism.The fixed base 50 is located below the arm mechanism 14. This allows thearm mechanism 14 to be placed relatively high up in the spring balancedsupport device, above an area where an operator is located. Furthermore,this configuration allows longer lengths of the springs which results ina more constant spring force over the operating range.

A spring base point 52 in the form of two pulleys 53A, 53B is locatedabove the elbows 32, 34. The springs 36, 37 extend from the fixed base50 to the spring base point 52 and from the spring base point 52 to theright and left elbows 32, 34. It is noted that the spring 36 may endbelow the spring base point 52, but a spring cable 55 continues from thepoint onward. One spring cable 55 is guided over pulley 53A and onespring cable 55 is guided over pulley 53B. The pulleys 53A, 53B arerotatable. The movable base 42 is positioned vertically underneath thespring base point 52, i.e. along a same vertical axis 17. The springcables 55 cross one another at the spring support, i.e. the left spring36 is connected to the right arm 21 and the right spring 37 is connectedto the left arm 23.

The elbows are also provided as pulleys 56, 57 which are fixed to therespective lower arms 22, 24. The pulleys 56, 57 act as curved supportsurfaces and allow the ends 38, 39 of the springs to engage the elbows32, 34 without excessive local bending moments in the ends 38, 39 of thesprings.

The carriage 61 is guided by the vertical rail 62 and is not connecteddirectly to the arm mechanism 14. Instead, the carriage 61 is connectedto a pulley device 90 which in turn is connected to the arm mechanism 14via a transmission 100. The pulley device 90 comprises an upper pulley92, a lower pulley 94 and a cable 96. The carriage 61 is fixed to thecable 96.

The upper pulley 92 comprises a large pulley wheel 92A and a smallpulley wheel 92B. The cable 96 is guided over the large pulley wheel92A. The small pulley wheel 92B is connected to the transmission device100 via a cable 101. The cable 92 is connected to a pulley 104 of thetransmission device. The pulley 104 comprises two pulley wheels 104A,104B. The pulley wheel 104B is connected via another cable 102 to asecond pulley 105 of the transmission device. The cable 102 is connectedto the upper corner 31 of the arm mechanism 14. This is where the masscoupling point 200 and the upper movable pivot point 25 are located.

This embodiment achieves a relatively large operating range of the masssupport member 18 because a large vertical movement 48 of the masssupport member 18 is transferred into a relatively small verticalmovement of the upper corner 31 of the arm mechanism 14.

The spring balanced support device further comprises a brake member 127which brakes the upper pulley 92. The brake device 126 further comprisesa brake member 128 for the arm 60. The brake member 128 comprises a shoewhich brakes the sliding or rolling mechanism 67 in order to fixate thesegments 66, 68 relative to one another. The brake members 127, 128 areoperated with respective actuators 131, 133 which are coupled to thecontrol device 72 via connection lines 134, 135.

The segmented horizontal arm 60 allows small horizontal movements, seearrow 70. The wagon 82 allows large horizontal movements along the rail80, see arrow 86.

The brake device 126 comprises a further brake member 129 which brakesthe hinge 110 having a vertical hinge axis 112 and a further brakemember 129 a which brakes the hinge 110 a having a vertical hinge axis112 a. Therefore, the brake 126 brakes one or more of the following fourdifferent movements:

1) brake member 127 for braking the vertical movement of movable support61,

2) brake member 128 for braking the horizontal movement of segment 68relative to segment 66, and

3) brake member 129 for braking the pivoting movement of arm 60 aboutpivot axis 112.

4) brake member 129 a for braking the pivoting movement about axis 112 aof the mass 12 on platform 18.

All four brakes members may be connected to the control device 72 viacommunication lines 134. Only the brake member 127 on the movablesupport 61 is required for adjusting the movable pivot point 76. Theother three brake members 128, 129 and 129 a make the spring balancedsupport device more practical in its operation. The brake member 127 canbe released when the adjusting process is finished. The brake members128, 129 and 129 a can be released earlier than the brake member 127.The four brake members can be used in other embodiments as well. Thebrake members may also be operated manually or triggered by a switch 136which may be connected to control unit 72.

In operation, the object 12 is placed on the platform 18. The brakedevice 126 is turned on in order to fixate the vertical position of themass support member 18 and the object 12. The sliding or rollingmechanism 67 is also fixated. The weight is measured and the movablebase 42 is adjusted in order to balance the weight. This only takes arelatively short period of time for most objects. The object can then bemoved in a horizontal direction and a vertical direction. When theobject 12 is moved upwards, the cable 96 rotates the pulley 92.

The pulley 92 rotates the cable 101 which in turn rotates the pulley104. The pulley 104 rotates the cable 102 which moves the upper corner31 of the arm mechanism 14 up or down.

The skilled person will understand that the horizontal arm 60 and thevertical arm 84 need not be oriented exactly horizontally or vertically,but may be oriented at a slight angle.

The embodiment of FIG. 4A having two arms can be combined with many ofthe features of the embodiment of FIG. 4B, such as the pulley device 90,the transmission device 100, the spring base point 52 in the form of apulley, the pulley 56 at the elbow and/or the brake device 126comprising the brake members 127, 128, 129.

In another embodiment, the weighing device comprises an accelerometer.The accelerometer allows the weighing operation to take place in motion,i.e. without the brake device 126 being activated. Accelerometers areknown in the field of the art.

Turning to FIGS. 5A and 5B, an embodiment is shown which is based on theembodiment of FIGS. 4A, 4B. The wagon 82 comprises wheels 83 which aresupported by a rail 80 which is not shown. The frame 84 extendsdownwards from the wagon. A housing 85 is provided to cover the frame 84and the parts of the spring balanced support device. The arm mechanism14 is provided inside the housing 85, near an upper end thereof andinside an upper part of the housing which is wider than a lower part ofthe housing.

The protruding arm 60 is rotatable about the hinge 110 to provide full3D movement of the mass support member 18. The mass support member 18 isa platform, in particular a circular disc. The protruding arm 60 is atelescoping arm comprising two segments 66, 68. Segment 68 telescopesinside segment 66.

The spring balanced support device 10 is positioned at a transportconveyor 118 for suitcases. An operator 120 stand adjacent the transportconveyor and pulls a suitcase from the transport conveyor onto the masssupport member 18. The brake device 126 is activated to fix the verticalposition. Additionally, the pivoting movement of arm 60 at hinge 110 andthe telescoping movement of arm 60 may be fixated by the brake. Next,the weighing device 16 weighs the suitcase and adjusts the movable base42 via the control device and the actuator. The brake device 126 issubsequently de-activated. The operator can then simply lift thesuitcase in any direction he wants, for instance onto a container orwagon 122 holding many suitcases. A movement in a reversed direction isalso possible of course, i.e. the operator can load the suitcases fromthe container or wagon 122 onto the transport conveyor 118. Because theoperator needs very little force, the working environment issubstantially improved.

It will be clear to the skilled person that the spring balanced supportdevice according to the invention may be free of any motor for movingthe object in a horizontal direction or vertical direction, the springbalanced support device allowing the movement in a horizontal andvertical direction by manual labour and therefore more intuitiveoperation only.

An overhead rail 80 and a wagon 82 which comprises wheels 83 and ismovable in a horizontal direction 86 along said rail 80. An upper rail80 and a lower rail 80 are provided to fixate the wagon between therails 80. A vertical frame 84 or vertical arm 84 is suspended from thewagon 82 and fixed to said wagon. Moments from the frame 84 can betransferred to the rail 80 via the wagon 82.

The embodiment has two arms 21, 22, i.e. a lower arm 21 and an upper arm22. The embodiment has a single elbow and a single spring 36. It isnoted that the single spring 36 may be replaced by two or more springs,for instance parallel springs, if needed. It is also possible todistribute the force of a single spring over a left side and a rightside of an arm mechanism.

A rail 43 is provided which extends vertically and guides both themovable base 42 and the mass coupling point 200 at the end 19 of theupper arm 22. The upper end 28 of the upper arm 22 is held in a fixedhorizontal position by the rail 43.

The horizontal arm 60 comprises a first segment 66 and a second segment68 which are slideably arranged relative to one another via a sliding orrolling mechanism 67. This configuration allows a horizontal movement ofthe object which is indicated by arrow 70. The horizontal movement andthe vertical movement together allow a movement in two dimensions withlittle effort. The mass support member 18 is a platform on which theobject 12 may rest.

The carriage 61 further comprises a hinge 110 having a vertical axis112. The hinge 110 allows rotation of the horizontal arm 60 about thevertical axis 112, thereby allowing a movement of the object 12 in threedimensions.

Turning to FIG. 6A, it is shown that one aspect of the invention can beregarded independently and can be applied in any kind of spring balancedsupport device. This relates to the combination of weighing device,control device and adjusting mechanism.

FIG. 6A shows a spring balanced support device 1 according to the priorart, i.e. as shown in FIG. 1, but further comprising the combination ofa weighing device 16, a control unit 72 and an adjusting mechanism 44comprising an actuator 45. The actuator is coupled to the base 5 foradjusting the spring 3. With this embodiment, a rapid adjustment of thespring balanced support device to a variable weight is also possible,allowing pick and place operations. The embodiment of FIG. 9 provides asubstantial improvement over the prior art. The weighing device 16 canbe provided with a accelerometer if required. Alternatively or incombination with the actuator which is coupled to the base 5, anactuator 45 b may be provided on the arm which is coupled to the slider8. A brake device may also be provided.

Turning to FIG. 6B, an embodiment is shown having two arms 21, 22 and aspring connection point 27 which is movable in a cam on the arm 21 by anactuator 45 b. The lower end 29 of the first arm 21 is connected to afixed base. The spring base point 52 is connected to a movable base 125and is movable with actuator 45. In this embodiment, both ends of thespring can be adjusted. In use, the control device 72 receives theweight signal from the weighing device 16 and transmit a actuationsignal to the actuators 45, 45 b. As required, detailed embodiments ofthe present invention are disclosed herein; however, it is to beunderstood that the disclosed embodiments are merely exemplary of theinvention, which can be embodied in various forms. Therefore, specificstructural and functional details disclosed herein are not to beinterpreted as limiting, but merely as a basis for the claims and as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention in virtually any appropriately detailedstructure. Further, the terms and phrases used herein are not intendedto be limiting, but rather, to provide an understandable description ofthe invention.

The terms “a” or “an”, as used herein, are defined as one or more thanone. The term plurality, as used herein, is defined as two or more thantwo. The term another, as used herein, is defined as at least a secondor more. The terms including and/or having, as used herein, are definedas comprising (i.e., open language, not excluding other elements orsteps). Any reference signs in the claims should not be construed aslimiting the scope of the claims or the invention.

The mere fact that certain measures are recited in mutually differentdependent claims does not indicate that a combination of these measurescannot be used to advantage.

1-41. (canceled)
 42. A spring balanced support device comprising: atleast a first arm, connected to its surroundings via a first movablepivot point which is movable along an axis, and a second arm, connectedto the first arm at an elbow pivot point, wherein the second arm isfurther coupled to the surroundings via a second movable pivot pointwhich is movable substantially parallel to said axis, the first andsecond arm forming an arm mechanism to which a mass may be coupleddirectly or indirectly at a mass coupling point, balanced by at leastone spring, one end of the spring connected to the arm mechanism at aspring connection point and, the other end of the spring directly orindirectly connected to the surroundings at a spring base point; whereinthe spring base point is located substantially on the axis which extendsthrough the first movable pivot point and substantially parallel to adirection of a force exerted on the spring balanced support device atthe mass coupling point due to the force of gravity on the mass, orwherein the spring base point is located at a distance from said axisalong a line which intersects the axis and which extends substantiallyparallel to a pivot point axis of the first movable pivot point, whereinthe first movable pivot point is movable along the axis in order toadjust the spring balanced support device.
 43. The spring balancedsupport device according to claim 42, wherein the arm mechanism is notconnected to any fixed base and wherein each part of the arm mechanismis movable at least in a direction parallel to the axis.
 44. The springbalanced support device according to claim 42, wherein the position ofthe spring connection point is fixed and non-adjustable, and wherein theposition of the spring base point is fixed and non-adjustable.
 45. Thespring balanced support device according to claim 42, wherein the secondmovable pivot point is operable to be positioned at a predetermineddistance from the spring base point, wherein a change in potentialenergy of the arm mechanism as a result of a movement of the first pivotpoint is substantially the same as a change in spring energy in theleast one spring as a result of said movement.
 46. The spring balancedsupport device according to claim 42, wherein the second movable pivotpoint is operable to be positioned near the spring base point andbetween the spring base point and the first movable pivot point duringthe adjusting process.
 47. The spring balanced support device accordingto claim 42, further comprising a brake device constructed to: during anadjusting step, fixate a position of the mass coupling point along saidaxis while allowing a movement of the first movable pivot point alongsaid axis, and/or; during a balancing step, fixate the position of thefirst movable pivot point along said axis while allowing a movement ofmass coupling point along said axis.
 48. The spring balanced supportdevice according to claim 42, wherein the spring balanced support devicefurther comprises: a weighing device configured to weigh the mass whichis supported by a mass support member; an actuator being constructed tomove the first movable pivot point; a control device being connected tothe weighing device and to the actuator; and wherein the control deviceis configured to control the actuator for adjusting the position of thefirst movable pivot point on the basis of a signal of the weighingdevice which is indicative of the measured weight of the mass.
 49. Thespring balanced support device according to claim 48, wherein the brakedevice is coupled to the control device, the control device beingconfigured to fixate the position of the mass coupling point along theaxis during the weighing of the mass.
 50. The spring balanced supportdevice according to claim 48, comprising: a wagon comprising wheels orskidding members; and a frame being connected to said wagon, the frameextending over a vertical distance wherein the arm mechanism and atleast one spring are connected to said frame.
 51. The spring balancedsupport device according to claim 42, comprising a transmission devicebeing mechanically interposed between the mass and the arm mechanism,the transmission device being configured to cause a ratio of a verticalmovement of the mass coupling point and a vertical movement of the massitself to be less than 1:1.25 or more than 1:0.75.
 52. The springbalanced support device according to claim 48, comprising a protrudingarm which is connected directly or indirectly to the arm mechanism,wherein the protruding arm extends over a horizontal distance, whereinthe protruding arm is connected to a carriage which is guided by a railwhich extends parallel to said axis; wherein the protruding arm isconnected to the arm mechanism via a hinge having a vertical axis.
 53. Aspring balanced support device according to claim 42, further comprisinga pulley device comprising an upper pulley, a lower pulley and anendless flexible member being supported by the upper and lower pulleyand extending at least in part parallel to said rail, wherein the massis connected to the mass coupling point via said endless flexiblemember.
 54. A spring balanced support device according to claim 52,comprising one or more of the following brake members: 1) a first brakemember for braking a vertical movement of the mass, 2) a second brakemember for braking a horizontal movement of the second arm segmentrelative to the first arm segment, 3) a third brake member for brakingthe pivoting movement of the protruding arm about said vertical axis ofsaid hinge, and/or, 4) a fourth brake member for braking the pivotingmovement of the mass about a pivot axis, wherein the one or more brakemembers are connected to the control device via communication lines, thecontrol device being configured to switch the one of more brake memberson or off, together or separately.
 55. A method of supporting a mass,the method comprising: providing a spring balanced support devicecomprising at least a first arm, connected to its surroundings via afirst movable pivot point which is movable along an axis, and a secondarm, connected to the first arm at an elbow pivot point, wherein thesecond arm is further coupled to the surroundings via a second movablepivot point which is movable substantially parallel to said axis, thefirst and second arm forming an arm mechanism to which a mass may becoupled directly or indirectly at a mass coupling point, balanced by atleast one spring, one end of the spring connected to the arm mechanismat a spring connection point, the other end of the spring directly orindirectly connected to the surroundings at a spring base point; whereinthe spring base point is located substantially on the axis which extendsthrough the first movable pivot point and substantially parallel to adirection of a force exerted on the spring balanced support device atthe mass coupling point due to the force of gravity on the mass, orwherein the spring base point is located at a distance from said axisalong a line which intersects the axis and which extends substantiallyparallel to a pivot point axis of the first movable pivot point, whereinthe first movable pivot point is movable along the axis in order toadjust the spring balanced support device, further comprising the stepsof: engaging the mass with the spring balanced support device, adjustingthe position of the first movable pivot point so that the springbalanced support device generates a spring force which balances theweight of the mass, and moving the mass relative to the spring balancedsupport device.
 56. A method according to claim 55, wherein the springbase point is located substantially along said axis and within anoperating range of the second movable pivot point along said axis, themethod further comprising engaging or disengaging the mass by the springbalanced support device in a position wherein the second movable pivotpoint is positioned at or near the position of the spring base pointalong said axis, in which position a change in potential energy of thearm mechanism as a result of the moving of the first movable pivot pointis substantially the same as a change in spring energy in the at leastone spring; wherein the second movable pivot point is positioned betweenthe first movable pivot point and the spring base point at the moment ofengagement.